Rising Diabetes Prevalence among Urban-Dwelling Black South Africans

Objective

To examine the prevalence of and the association of psychosocial risk factors with diabetes in 25–74-year-old black Africans in Cape Town in 2008/09 and to compare the prevalence with a 1990 study.

Research Design and Methods

A randomly selected cross-sectional sample had oral glucose tolerance tests. The prevalence of diabetes (1998 WHO criteria), other cardiovascular risk factors and psychosocial measures, including sense of coherence (SOC), locus of control and adverse life events, were determined. The comparison of diabetes prevalence between this and a 1990 study used the 1985 WHO diabetes criteria.

Results

There were 1099 participants, 392 men and 707 women (response rate 86%). The age-standardised (SEGI) prevalence of diabetes was 13.1% (95% confidence interval (CI) 11.0–15.1), impaired glucose tolerance (IGT) 11.2% (9.2–13.1) and impaired fasting glycaemia 1.2% (0.6–1.9). Diabetes prevalence peaked in 65–74-year-olds (38.6%). Among diabetic participants, 57.9% were known and 38.6% treated. Using 1985 WHO criteria, age-standardised diabetes prevalence was higher by 53% in 2008/09 (12.2% (10.2–14.2)) compared to 1990 (8.0% (5.8–10.3)) and IGT by 67% (2008/09: 11.7% (9.8–13.7); 1990: 7.0% (4.9–9.1)). In women, older age (OR: 1.05, 95%CI: 1.03–1.08, p<0.001), diabetes family history (OR: 3.13, 95%CI: 1.92–5.12, p<0.001), higher BMI (OR: 1.44, 95%CI: 1.20–1.82, p = 0.001), better quality housing (OR: 2.08, 95%CI: 1.01–3.04, p = 0.047) and a lower SOC score (≤40) was positively associated with diabetes (OR: 2.57, 95%CI: 1.37–4.80, p = 0.003). Diabetes was not associated with the other psychosocial measures in women or with any psychosocial measure in men. Only older age (OR: 1.05, 95%CI: 1.02–1.08, p = 0.002) and higher BMI (OR: 1.10, 95%CI: 1.04–1.18, p = 0.003) were significantly associated with diabetes in men.

Conclusions

The current high prevalence of diabetes in urban-dwelling South Africans, and the likelihood of further rises given the high rates of IGT and obesity, is concerning. Multi-facetted diabetes prevention strategies are essential to address this burden.     

A longitudinal study of rheumatoid arthritis in South Africans

Little is known about the functional outcome of rheumatoid arthritis (RA) in Africans treated with disease-modifying antirheumatic drugs (DMARDs). We describe our experience with 182 RA patients seen at a tertiary hospital in South Africa. During the median follow-up period of 3.3 years, the proportion of patients with severe functional disability (American College of Rheumatology [ACR] functional classes [FCs] 3 and 4) declined significantly from 48.9% at presentation to 30.8% at last visit (P =.0006). There was a significant fall in the median Westergren erythrocyte sedimentation rate (ESR) (46-28 mm/hour, P <.00001) and C-reactive protein (CRP) (19-15.5 mg/L, P =.006) over this period. Logistic regression analysis showed that the factors that negatively affected functional outcome at last visit were severe functional disability at presentation (odds ratio [OR] = 4.1, P =.0004), delay in referral for specialist care > 2 years (OR = 3.1, P =.02), and ESR at last visit > 28 mm/hour (OR = 3.2, P =.002). DMARDs and oral corticosteroids were prescribed in 93.1% of patients at presentation and 60.4% of patients at last visit. Life-table analysis showed that the survival time with methotrexate (MTX) use was significantly longer compared with the other DMARDs (P =.0002). A total of only 37 surgical procedures were performed on 21 patients. This retrospective study shows that despite the late presentation and severe disease, patients do improve on DMARD therapy in the medium term. The study highlights the need for prospective studies to assess the efficacy and safety of DMARDs, particularly in early disease, in the developing countries where biologics are unlikely to be affordable in the foreseeable future.     

Geometric morphometric analysis of the greater sciatic notch in South Africans

The width of the greater sciatic notch of the pelvis is a characteristic commonly used to determine sex in unknown individuals. Recent research on South African skeletal material indicated that this feature may not be so reliable, especially in South African white males. In this study the greater sciatic notches of 115 known skeletons of South African origin were analysed using geometric morphometrics. Geometric morphometrics is a relatively new method that helps to quantify shape. Using this method, it was observed that South African black males have the typical narrow shape, while both the black and white females have typical wide notches. The white males, however, showed a very wide variation and their shapes scattered across the range. The shape of the greater sciatic notch is therefore not reliable to use in sex determination in this population group. Geometric morphometric analysis proved to be a valuable and reliable method to verify morphological characteristics observed with more traditional methods.     

Trial of atenolol and chlorthalidone for hypertension in black South Africans.

Twenty-four black patients (Zulus) with hypertension participated in a double-blind, placebo-controlled cross-over trial of the efficacy of a beta-blocking agent (atenolol) 100 mg once daily as compared with chlorthalidone 25 mg once daily. The two drugs were also given combined at these doses and the effects compared with those of the drugs given alone. Atenolol as sole treatment had no appreciable effect on blood pressure as compared with placebo. Chlorthalidone produced a small decrease, but this was not statistically significant. Combining the two drugs, however, produced a significant reduction in blood pressure (mean lying blood pressure p < 0.001; mean standing blood pressure p < 0.0002). These findings suggest that beta-blockers should not be regarded as baseline treatment of hypertension in blacks.     

Founder effect and prevalence of myotonic dystrophy in South Africans: molecular studies.

A high prevalence of myotonic dystrophy (DM) has been described in South African Caucasoid Afrikaans-speaking families in the northern Transvaal. Evidence is presented for a strong founder effect, with a single haplotype occurring on 68% of all Caucasoid DM chromosomes; among the Afrikaans speakers, the proportion was 83%. In addition to this major haplotype, five minor DM haplotypes in the Caucasoids and two minor haplotypes in DM individuals of mixed ancestry were found. All DM chromosomes, however, had a common haplotype core, namely, Alu (ins), HinfI-2 (intron 9), and TaqI-2 (D19S463). We have detected significant linkage disequilibrium between the DM mutation and particular alleles of the extragenic markers D19S112 and D19S207. Significant differences were found in allele and haplotype distributions in the Caucasoid DM and non-DM chromosomes and Negroid non-DM chromosomes. These findings together with the strong association of allele 3 at the D19S63 locus on 93% (14/15) of the South African DM chromosomes suggest that the majority of present-day DM mutations in South African Caucasoids may have originated from a common initial founder who introduced one of the European ancestral mutations.     

An assessment of sex using the skull of black South Africans by discriminant function analysis

The derivation of discriminant function equations for skeletal elements of South African populations continues to be an area of interest to both forensic anthropologists and skeletal biologists alike. The skull of black South Africans has previously been subjected to discriminant function analysis, using four measurements and two indices; however, no equations were derived to address the issue of sex determination. Recently Franklin, Freedman and Milne [2005. Sexual dimorphism and discriminant function sexing in indigenous South African crania. HOMO J. Comp. Hum. Biol. 55, 213-228] used the crania of black South Africans, in a three-dimensional approach, with eight linear measurements to investigate sex determination. This study, although valuable, requires the use of highly technical and expensive morphometric equipment that renders it less feasible in South Africa. In response to this, our study uses traditional anthropometric measurements and equipment to address the question of sex determination from the crania and mandible of blacks. One hundred and twenty non-pathological skulls were randomly selected from the Raymond Dart Collection of Human Skeletons, equally distributed by sex and belonging to individuals whose age at death ranges between 25 and 70 years. Fourteen cranial and six mandibular measurements were subjected to discriminant function analyses and discriminant function equations were derived for sex determination. Average accuracies ranged between 80% and 85% and were on par with that obtained in previous studies. Our study shows that traditional methods provide average accuracies that are comparable to those obtained using more complex techniques.     

DNA methylation similarities in genes of black South Africans with systemic lupus erythematosus and systemic sclerosis

Background

Systemic lupus erythematosus (SLE) and systemic sclerosis (SSc) are systemic autoimmune connective tissue diseases that share overlapping clinico-pathological features. It is highly probable that there is an overlap in epigenetic landscapes of both diseases. This study aimed to identify similarities in DNA methylation changes in genes involved in SLE and SSc. Global DNA methylation and twelve genes selected on the basis of their involvement in inflammation, autoimmunity and/or fibrosis were analyzed using PCR arrays in three groups, each of 30 Black South Africans with SLE and SSc, plus 40 healthy control subjects.

Results

Global methylation in both diseases was significantly lower (<25 %) than in healthy subjects (>30 %, p = 0.0000001). In comparison to healthy controls, a similar gene-specific methylation pattern was observed in both SLE and SSc. Three genes, namely; PRF1, ITGAL and FOXP3 were consistently hypermethylated while CDKN2A and CD70 were hypomethylated in both diseases. The other genes (SOCS1, CTGF, THY1, CXCR4, MT1-G, FLI1, and DNMT1) were generally hypomethylated in SLE whereas they were neither hyper- nor hypo-methylated in SSc.

Conclusions

SSc and SLE patients have a higher global hypomethylation than healthy subjects with specific genes being hypomethylated and others hypermethylated. The majority of genes studied were hypomethylated in SLE compared to SSc. In addition to the commonly known hypomethylated genes in SLE and SSc, there are other hypomethylated genes (such as MT-1G and THY-1) that have not previously been investigated in SLE and SSc though are known to be hypermethylated in cancer.